Stud bump for wirebonding high voltage isolation barrier connection

ABSTRACT

An electronic device includes a bond wire with a first end bonded by a ball bond to a planar side of a first conductive plate, and a second end bonded by a stitch bond to a conductive stud bump at an angle greater than or equal to 60 degrees. A wirebonding method includes bonding the first end of the conductive bond wire to the first conductive plate includes forming a ball bond to join the first end of the conductive bond wire to a planar side of the first conductive plate by a ball bond, and bonding the second end of the conductive bond wire to the conductive stud bump includes forming a stitch bond to join the second end of the conductive bond wire to the conductive stud bump.

BACKGROUND

High voltage isolation barriers are used in electronic power converterand communications devices, to transfer power or signaling betweendifferent voltage domains. Close spacing between high voltage isolationbarrier components can lead to undesirable dielectric breakdown orarcing. Wirebonding capacitor plates of different voltage domainspresents problems in avoiding arcing, particularly for low profiledevices with short loop height restrictions. Insufficient wire stitchangle in a wire bond connection can induce an electrical breakdown andarcing issue for high voltage isolation.

SUMMARY

In one aspect, a packaged electronic device includes first and secondsemiconductor dies with respective plates coupled by a conductive bondwire, and the second plate has a conductive stud bump. The bond wire hasa first end bonded to a planar side of the first conductive plate. Thesecond end of the conductive bond wire is bonded to the conductive studbump at an angle greater than or equal to 60 degrees to a planar side ofthe second conductive plate.

In another aspect, a method of manufacturing a packaged electronicdevice includes fabricating a first semiconductor die having a firstconductive plate, fabricating a second semiconductor die having a secondconductive plate, attaching the first semiconductor die to a first dieattach pad and attaching the second semiconductor die to a second dieattach pad. The method further includes forming a conductive stud bumpextending outward from a planar side of the second conductive plate,bonding a first end of a conductive bond wire to the first conductiveplate, as well as bonding a second end of the conductive bond wire tothe conductive stud bump at an angle of 60 degrees or more to a plane ofa planar side of the second conductive plate and forming a packagestructure to enclose the first semiconductor die, the secondsemiconductor die, the conductive stud bump and the conductive bondwire.

In a further aspect, a wirebonding method includes forming a conductivestud bump on a planar side of a second conductive plate, forming a ballbond that joins a first end of a conductive bond wire to a firstconductive plate and forming a stitch bond that joins a second end ofthe conductive bond wire to the conductive stud bump using a wirebonding tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side elevation view of a packaged electronicdevice with a bond wire connecting capacitor plates with elevated studbumps.

FIG. 1A is a top plan view of the packaged electronic device of FIG. 1.

FIG. 1B is a partial perspective view of an example of the bond wireconnection in the packaged electronic device of FIG. 1.

FIG. 1C is a partial perspective view of one connection of a bond wireto an elevated stud bump in the packaged electronic device of FIG. 1.

FIG. 1D is a partial perspective view of an elevated stud bump in thepackaged electronic device of FIG. 1.

FIG. 1E is a partial perspective view of several bond wires connected torespective elevated stud bumps in the packaged electronic device of FIG.1.

FIG. 2 is a flow diagram of a method of manufacturing a packagedelectronic device.

FIGS. 3-5 are sectional side elevation views of the packaged electronicdevice of FIG. 1 undergoing fabrication processing according to themethod of FIG. 2.

FIG. 6 is a flow diagram of a wire bonding process.

FIGS. 7-32 are partial side views of the packaged electronic device ofFIG. 1 undergoing wire bonding processing according to the method ofFIG. 6.

DETAILED DESCRIPTION

In the drawings, like reference numerals refer to like elementsthroughout, and the various features are not necessarily drawn to scale.Also, the term “couple” or “couples” includes indirect or directelectrical or mechanical connection or combinations thereof. Forexample, if a first device couples to or is coupled with a seconddevice, that connection may be through a direct electrical connection,or through an indirect electrical connection via one or more interveningdevices and connections. One or more operational characteristics ofvarious circuits, systems and/or components are hereinafter described inthe context of functions which in some cases result from configurationand/or interconnection of various structures when circuitry is poweredand operating.

FIGS. 1A-1D show a packaged electronic device 100 with a bond wireconnecting capacitor plates using elevated stud bumps. FIG. 1 shows asectional side view along section line 1-1 in the top view of FIG. 1A.FIG. 1B shows an example of a bond wire connection and FIG. 1C shows oneconnection of a bond wire to half or less of an elevated stud bump,referred to as an “Atlas Stud bump”, in the packaged electronic device100. FIG. 1D shows an example elevated stud bump and FIG. 1E showsseveral bond wires connected to respective elevated stud bumps in thepackaged electronic device 100.

The packaged electronic device 100 includes a package structure 108 witha first side 101 (e.g., the bottom side in the illustrated orientationof FIG. 1) and an opposite second side 102 (e.g., top) spaced apart fromthe first side 101 along a first direction (e.g., the vertical directionZ in FIGS. 1 and 1B). The packaged electronic device 100 also includes athird side 103 (e.g., the lateral left side in FIGS. 1, lA and 1B) andan opposite fourth side 104 (e.g., right side) spaced apart from thethird side 103 along a second direction (e.g., the X direction), wherethe second direction X is orthogonal to the first direction Z. Thepackaged electronic device 100 in the illustrated example is generallyrectangular and includes lateral ends formed by a fifth side 105 and asixth side 106 (FIG. 1A). The sixth side 106 is spaced apart from thefifth side 105 along a third direction Y that is orthogonal to therespective first and second directions Z and X. The packaged electronicdevice 100 in this example has generally flat or planar bottom and topsides 101 and 102. The lateral sides 103-106 can be tapered from a moldparting line to facilitate ejection from a mold during fabrication. Inother implementations, one or more of the lateral sides 103-106 can beflat or planar and/or one or both sides 101 and 102 can be non-planar.The packaged electronic device 100 has a set of gull wing first leads111 that extend outward and down from the third side 103, and a set ofgull wing second leads 112 that extend outward and down from the fourthside 104.

As best shown in the sectional view of FIG. 1, the packaged electronicdevice 100 includes a first conductive die attach pad 120, with a firstsemiconductor die 121, 122 mounted thereon. The first semiconductor dieincludes a semiconductor portion 121 and a metallization structure 122on a top side of the semiconductor portion 121. The first semiconductordie 121, 122 includes a first capacitor 124 having a lower capacitorplate 126 and an upper or first capacitor plate 128 separated or spacedapart from one another by a dielectric material of the firstmetallization structure 122. The first conductive plate 128 has a planartop side with a connection 130. The metallization structure 122 of thefirst semiconductor die 121, 122 in this example also includes a bondpad 132 having an exposed upper side with a bond wire connection 134that connects to a bond wire 136, which electrically couples the bondpad 132 to the first lead 111.

A conductive bond wire 137 includes a first end 138 that is bonded tothe planar top side of the first conductive plate 138 by the connection130. The conductive bond wire 137 also includes a second end 139. Thefirst end 138 of the conductive bond wire 137 is joined to the firstconductive plate 128 at a first angle θ1 to a plane of the planar sideof the first conductive plate 128. In one example, the first angle θ1 isgreater than or equal to 60 degrees and may be as much as 90 degrees incertain examples. In one example, the connection 130 is a ball bondformed by a wire bonding tool as described further below.

The packaged electronic device 100 in FIG. 1 also has a second dieattach pad 140 with a second semiconductor die 141, 142 thereon. Thesecond semiconductor die includes a semiconductor portion 141 and ametallization structure 142 on a top side of the semiconductor portion141. The second semiconductor die 141, 142 includes a second capacitor144 with a lower capacitor plate 146 and an upper or second conductiveplate 148 separated or spaced apart from one another by a dielectricmaterial of the metallization structure 142. A conductive stud bump 150is bonded to, and extends outward from, a planar side of the secondconductive plate 148. The metallization structure 142 includes a bondpad 152 with an exposed upper side having a bond wire connection 154that connects to another bond wire 156 to electrically couple the bondpad 152 to the second lead 112. The package structure 108 encloses thefirst semiconductor die 121, 122, the second semiconductor die 141, 142,the conductive stud bump 150 and the conductive bond wires 136, 137 and156, as well as interior portions of the leads 111 and 112.

The second end 139 of the conductive bond wire 137 bonded to theconductive stud bump 150. The second end 139 is joined to the conductivestud bump 150 at a second angle θ2 to the plane of the planar side ofthe second conductive plate 148. In one example, the second end 139 ofthe conductive bond wire 137 is bonded to the conductive stud bump 150by a stitch bond using the wire bonding tool. In one example, the secondangle θ2 is greater than or equal to 60 degrees. In one implementation,the second angle θ2 is less than or equal to 75 degrees. In anotherexample, the second angle θ2 is less than or equal to 70 degrees. In oneimplementation, the stitch bond of the second end 139 joins half or lessof the conductive stud bump 150 to further facilitate an increasedsecond angle θ2 with respect to the plane of the top side of the secondconductive plate 148.

The bond wire joint angles θ1 and θ2 are each above 60 degrees, whereasconventional wire bonding structures and techniques typically achieve 30to 40 degrees, particularly for stich bonds. The increase bond wirejoint angles θ1 and θ2 are advantageous for bonding to electricalcomponents, such as the capacitors 124 and 144 where the components arecoupled at a high voltage isolation boundary. In one example, the firstsemiconductor die 121, 122 operates in a first voltage domain when thepackaged electronic device 100 is powered and operating, whereas thesecond semiconductor die 141, 142 operates in a different second voltagedomain. The respective capacitors 124 and 144 are coupled in series withone another in this example to transfer signals across an isolationbarrier, in which the voltage of the conductive bond wire 137, and hencethe voltage of the upper conductive plates 128 and 148 can tens or evenhundreds of volts above or below the respective voltages of the lowercapacitor plates 126 and 146. The increased bond wire joint angles θ1and θ2 increases the spacing between the lower capacitor plates 126 and146 and the conductive bond wire 137. The increased spacing mitigatesdielectric breakdown and/or arcing while allowing increased voltagedifference between the first and second voltage domains along with thinoverall package dimensions without increasing loop height of the bondwire 137. In addition, the conductive stud bump 150, the connection 130and the bond wire 137 can be fabricated using a single wire bonding toolduring wire bond processing in one example, without significant increasein manufacturing cost or complexity, even for various loop height andwire length implementations.

Referring now to FIGS. 2-5, FIG. 2 shows a method 200 of fabricating apackaged electronic device and FIGS. 3-5 show side views of the packagedelectronic device 100 undergoing fabrication processing according to themethod 200. In one example, the semiconductor device fabrication usesstandard processing steps with a modified wirebonding process to formdie to die and die to lead electrical connections before forming apackage structure. The method 200 begins in FIG. 2 with die fabricationand die singulation at 202, for example, to produce the firstsemiconductor die 121, 122 having the first conductive plate 128 and thefirst bond pad 132, and the second semiconductor die 141, 142 having thesecond conductive plate 148 as shown in FIG. 1 above.

The method 200 continues with die attach processing at 204. FIG. 3 oneexample in which a die attach process 300 is performed that attaches thefirst semiconductor die 121, 122 to the first die attach pad 120 andattaches the second semiconductor die 141, 142 to the second die attachpad 140 of a starting lead frame that also includes unbent leads 111 and112. The die attach process 300 can use any suitable adhesive attachmentmaterials and steps, such as adhesive epoxy, soldering, etc. In oneexample, the starting lead frame includes an array with multiplesections that respectively correspond to a finished electronic device,and multiple sections may be processed concurrently. The lead frameincluding the unbent leads 111 and 112 and the die attach pads 120 and140 initially constitutes a unitary copper structure formed by suitablestamping operations, which may include features at different levels oron a single level as in the illustrated example. In one example, thestarting lead frame includes one or more support arms (not shown) thatsupport the die attach pads 120 and 140. Such support arm or arms can beconnected to portions of the lead frame to support the die attach pads120 and 140 during and after manufacturing or can be removed duringmanufacturing. In another example, the die attach pads 120 and 140 aresupported relative to the unbent lead portions 111 and 112 using anadhesive carrier or tape (not shown).

The method 200 continues at 206 in FIG. 2 with wire bonding. FIG. 4shows one example where a wire bonding process 400 is performed thatforms electrical connections by bond wires 136, 137 and 156. Thisexample includes forming the first bond wire 136 coupled between thefirst lead 111 and the bond pad 132 of the first semiconductor die 121,122, the bond wire 137 coupled between the conductive plates 128 and148, and the bond wire 156 coupled between the second lead 112 and thebond pad 152 of the second semiconductor die 141, 142.

At 208, a molding operation is performed to form a package structure.FIG. 5 shows one example in which the packaged electronic device 100undergoes a molding process 500 that forms the package structure 108having the sides 101-106 shown and described above. The packagestructure 108 encloses the first semiconductor die 121, 122, the secondsemiconductor die 141, 142, the conductive stud bump 150, the conductivebond wires 136, 137 and 156 and portions of the leads 111 and 112.

In one example, the method 200 also includes lead trimming and formingas well as dam bar cutting at 210 to remove copper dam bar featuresbetween the lead locations of a repeating lead pitch pattern. During themolding at 208, the dam bar features (not shown) mitigate or preventoutflow of molding material, after which the dam bar features areremoved at 210. The lead trimming in one example includes a lead cutprocess (not shown) that cuts ends of the leads 111 and 112 and leavesthe generally flat unbent leads as shown in the front view of FIG. 5. Incertain implementations, the method 200 also includes removal of anyincluded tie bars at 210. The lead forming at 210 includes bending orotherwise forming external portions of the trimmed leads 111 and 112into non-planar shapes, such as the gull wing forms shown in FIG. 1above. The method 200 further includes package separation at 212 forexample, by saw or laser cutting (not shown) and the resulting packagedelectronic device 100 is shown in FIGS. 1 and 1A discussed above.

Referring now to FIGS. 6-32, FIG. 6 shows a wire bonding process 600that can be used at 206 in FIG. 2 above, and FIGS. 7-32 show thepackaged electronic device 100 of FIG. 1 undergoing wire bondingprocessing according to the method 600. The method 600 begins at 602with forming a conductive stud bump on the conductive pad of asemiconductor die. FIGS. 7-23 show one example, in which the packagedelectronic device 100 undergoes the wire bonding process 600 to form theconductive stud bump 150 that extends outward from the planar top sideof the second conductive plate 148 of the second semiconductor die 141,142. The conductive stud bump 150 in one implementation is formed usinga wire bonding tool having a nozzle 700 for feeding a conductive wire702 from a spool or other source (not show), along with a clamp 704 andan electronic flame source 706. The wire bonding tool 700, 704, 706 inthis example is adapted for forming individual wire bonds with astarting ball bond and a finishing stitch bond by controlling theformation of a ball at the end of the wire 702 using the electronicflame source 706, controlling the position of the nozzle 700 inthree-dimensional (X, Y, Z) space by three- or four-dimensional controland actuators (not shown), and controlling opening and closure of theclamp 704. The wire bonding tool 700, 704, 706 in one example hasposition control apparatus, such as actuators (not shown) that areconfigured to implement wedge bonding and to control the nozzle 700 formovement in four axes of movement (e.g., X, Y, Z and an angle). In oneexample, the wire bonding tool 700, 704, 706 is configured to use anysuitable conductive wire 702, such as or including gold (Au), aluminum(Al), copper (Cu), etc.

As shown in FIG. 7, the clamp 704 is initially closed to hold the wire702, and the nozzle 700 is positioned close to the electronic flamesource 706. In FIG. 8, an electronic flame off (EFO) process isimplemented, in which the electronic flame source 706 is energized toform a flame or arc 800, which melts the end of the wire 702 to form aball 802 suspended by the remainder of the wire 702 while the clamp 704remains closed. The clamp 704 is then opened in FIG. 9, with the clamphalves separating along the directions of arrows 900, and the positioncontrol apparatus moves the nozzle 700 downward toward the planar topside of the second conductive plate 148 along the direction 1000 inFIGS. 10 and 11. The downward movement of the nozzle 700 continues withthe ball 802 touching the top side of the second conductive plate 148 inFIG. 12 and progressively collapsing and laterally spreading in FIGS. 13and 14 while the clamp 704 remains open.

With the ball 802 formed on the planar top side of the second conductiveplate 148 and the clamp 704 open, the position control apparatus movesthe nozzle 700 upward along the direction 1500 in FIG. 15, and thenlaterally (e.g., to the left) along the direction 1600 in FIG. 16 toextend the wire 702 laterally outward of the collapsed ball 802. Withthe clamp 704 still open in FIG. 17, the position control apparatusmoves the nozzle 700 upward along the direction 1700, and then laterallydownward at an angle as shown by the direction arrow 1800 in FIG. 18,followed by further downward lateral movement along the direction ofarrow 1900 in FIG. 19 while the clamp 704 remains open to curve the studbump with a bag shape. In FIGS. 20 and 21, the position controlapparatus moves the nozzle 700 upward along the direction 200 with theclamp 704 open to extend the wire 702 upward. In FIG. 22, the clamp 704is closed and the nozzle 700 continues to be raised along the upwarddirection 2000, and the continued movement along the direction 200causes the wire 702 to break as shown in FIG. 23 to complete theformation of the tall or elevated conductive stud bump 150 that extendsoutward (e.g., upward) from the planar top side of the second conductiveplate 148.

Referring again to FIG. 6 and to FIGS. 24-32, The wirebonding process600 continues at 604-612 in FIG. 6 with formation of the conductive bondwire 137 via a wire bonding process 2400. This includes bonding thefirst end 138 of the conductive bond wire 137 to the first conductiveplate 128 at 604 using the wire bonding tool 700, 704, 706. In oneexample, the first end 138 of the conductive bond wire 137 is bonded tothe first conductive plate 128 by forming 604 a ball bond to join thefirst end 138 of the conductive bond wire 137 to a planar side of thefirst conductive plate 128. The conductive bond wire is then extended at606 in FIG. 6 using the wire bonding tool 700, 704, 706 toward theconductive stud bump 150. The second end 139 of the conductive bond wire137 is the bonded at 608 to the conductive stud bump 150 at the angle θ2of 60 degrees or more to the plane of the planar side of the secondconductive plate 148. At 610, the bond wire is then raised away from theconductive stud bump 150, and the wire bonding tool 700, 704, 706 clampsand pulls the wire 702 at 612 to separate the wire 702 from the bondwire 137.

The process 2400 begins in FIG. 24 with the position control apparatusmoving the nozzle 700 close to the electronic flame source 706, andanother electronic flame off process is implemented, in which theelectronic flame source 706 is energized to form a flame or arc 800 tomelt the end of the wire 702 to form a ball 802 suspended by theremainder of the wire 702 while the clamp 704 remains closed as shown inFIG. 24. The clamp 704 is opened as shown in FIG. 25, and the positioncontrol apparatus moves the nozzle 700 downward in FIG. 26 along thedirection 2600 to move the ball 802 toward the first conductive plate128 with the clamp 704 open. The downward movement of the nozzle 700continues with the ball 802 touching the top side of the firstconductive plate 128 in FIG. 27 and progressively collapsing andlaterally spreading to form the first connection 130 while the clamp 704remains open. In one example, the connection 130 is a ball bond thatjoins a first end 138 of the prospective conductive bond wire 137 to thetop side of the first conductive plate 128. In one example, the positioncontrol apparatus vibrates the nozzle at high (e.g., ultrasonic)frequencies to bond the ball 802 to the top side of the conductive plate128 at 604 in FIG. 6 and as shown in FIG. 27, including lateral movementof the nozzle 700 back and forth along the X direction, or in a circularpattern in an X-Y plane, to form the ball bond connection 130.

Continuing in FIG. 28, the position control apparatus extends theconductive bond wire 137 upward and laterally away from the conductivestud bump 150 and the second conductive plate 148 along a direction ofthe arrow 2800 with the clamp 704 open, and then the clamp 704 is closedand the position control apparatus moves the nozzle 700 toward theconductive stud bump 150 (e.g., 606 in FIG. 6) along the direction 2900in FIG. 29 while the clamp 704 remains closed. The process 2400continues in FIG. 30 with the position control apparatus moving thenozzle 700 further laterally along the direction 2900 until the centerof the wire 700 is positioned above approximately half or less of theconductive stud bump 150 (e.g., above the tallest portion of theconductive stud bump) and then downward along the direction 3000 tocause the second end of the wire 137 to contact the conductive stud bump150. In one example, the position control apparatus vibrates the nozzleat high (e.g., ultrasonic) frequencies to bond the second end 139 of theconductive bond wire 137 to half or less of the top of the conductivestud bump 150 (608 in FIG. 6 above), for example, including lateralmovement of the nozzle 700 back and forth along the X direction, or in acircular pattern in an X-Y plane, to form the stitch bond connection.

In FIG. 31, with the clamp 704 opened, the position control apparatusmoves the nozzle 700 upward along the direction 3100. As shown in FIG.32 (610 in FIG. 6), the position control apparatus closes the clamp 704and raises the nozzle 700 upward along the direction 3100 further awayfrom the conductive stud bump 150 to separate or break the wire 702 fromthe second end 139 of the bond wire 137. This completes the stitch bondto join the second end 139 of the conductive bond wire 137 to theconductive stud bump 150 at the angle θ2 of 60 degrees or more to theplane of the planar side of the second conductive plate 148. In thisexample, moreover, the second angle θ2 is less than or equal to 75degrees and the stitch bond joins the second end 139 of the conductivebond wire 137 to half or less of the conductive stud bump 150. Thedescribed examples use the conductive stud bump 150 to holds up the wireloop and provide a steep stitch angle θ2 for a robust and stable wirebond connection to the top of the stud bump 150 for the wire landing.These examples can be constructed using conventional wire bonding toolsand process conditions without requiring additional or new equipment.Moreover, the loop height of the bond wire 137 can be lower tofacilitate reduced overall device package size while ensuring adequatespacing of the bond wire 137 from the lower capacitor plates 126 and 146to mitigate or avoid arcing or other dielectric breakdown. The aboveexamples also facilitate reduced manufacturing cost through use of lessmaterials and the shared use of a single wire bonding tool to fabricateall the bond wire connections in one example, while enhancing highvoltage package performance by less arcing.

Modifications are possible in the described examples, and otherimplementations are possible, within the scope of the claims.

What is claimed is:
 1. A packaged electronic device, comprising: a firstsemiconductor die having a first conductive plate; a secondsemiconductor die having a second conductive plate and a conductive studbump that extends outward from a planar side of the second conductiveplate; a conductive bond wire having a first end and a second end, thefirst end of the conductive bond wire bonded to a planar side of thefirst conductive plate, the second end of the conductive bond wirebonded to the conductive stud bump, the first end of the conductive bondwire joined to the first conductive plate at a first angle to a plane ofthe planar side of the first conductive plate, the second end joined tothe conductive stud bump at a second angle to the planar side of thesecond conductive plate, the first angle greater than or equal to 60degrees, and the second angle greater than or equal to 60 degrees. 2.The packaged electronic device of claim 1, wherein the second angle isless than or equal to 75 degrees.
 3. The packaged electronic device ofclaim 2, wherein the second angle is less than or equal to 70 degrees.4. The packaged electronic device of claim 2, wherein the first end ofthe conductive bond wire is bonded to a planar side of the firstconductive plate by a ball bond, and the second end of the conductivebond wire is bonded to the conductive stud bump by a stitch bond.
 5. Thepackaged electronic device of claim 4, wherein the stitch bond of thesecond end joins half or less of the conductive stud bump.
 6. Thepackaged electronic device of claim 2, wherein a stitch bond of thesecond end joins half or less of the conductive stud bump.
 7. Thepackaged electronic device of claim 1, wherein the first end of theconductive bond wire is bonded to a planar side of the first conductiveplate by a ball bond, and the second end of the conductive bond wire isbonded to the conductive stud bump by a stitch bond.
 8. The packagedelectronic device of claim 7, wherein the stitch bond of the second endjoins half or less of the conductive stud bump.
 9. The packagedelectronic device of claim 1, wherein a stitch bond of the second endjoins half or less of the conductive stud bump.
 10. The packagedelectronic device of claim 1, comprising a package structure thatencloses the first semiconductor die, the second semiconductor die, theconductive stud bump and the conductive bond wire.
 11. A method ofmanufacturing a packaged electronic device, the method comprising:fabricating a first semiconductor die having a first conductive plate;fabricating a second semiconductor die having a second conductive plate;attaching the first semiconductor die to a first die attach pad;attaching the second semiconductor die to a second die attach pad;forming a conductive stud bump extending outward from a planar side ofthe second conductive plate; bonding a first end of a conductive bondwire to the first conductive plate; bonding a second end of theconductive bond wire to the conductive stud bump at an angle of 60degrees or more to a plane of a planar side of the second conductiveplate; and forming a package structure to enclose the firstsemiconductor die, the second semiconductor die, the conductive studbump and the conductive bond wire.
 12. The method of claim 11, wherein:the conductive stud bump is formed using a wire bonding tool; the firstend of the conductive bond wire is bonded to the first conductive plateusing the wire bonding tool; and the second end of the conductive bondwire is bonded to the conductive stud bump using the wire bonding tool.13. The method of claim 11, wherein: bonding the first end of theconductive bond wire to the first conductive plate includes forming aball bond to join the first end of the conductive bond wire to a planarside of the first conductive plate; and bonding the second end of theconductive bond wire to the conductive stud bump includes forming astitch bond to join the second end of the conductive bond wire to theconductive stud bump.
 14. The method of claim 13, wherein the stitchbond of the second end joins half or less of the conductive stud bump.15. The method of claim 14, wherein the second angle is less than orequal to 75 degrees.
 16. The method of claim 11, wherein a stitch bondof the second end joins half or less of the conductive stud bump.
 17. Awirebonding method, comprising: using a wire bonding tool, forming aconductive stud bump on a planar side of a second conductive plate;using the wire bonding tool, forming a ball bond that joins a first endof a conductive bond wire to a first conductive plate; and using thewire bonding tool, forming a stitch bond that joins a second end of theconductive bond wire to the conductive stud bump.
 18. The wirebondingmethod of claim 17, wherein the stitch bond joins the second end of theconductive bond wire to the conductive stud bump at an angle of 60degrees or more to a plane of the planar side of the second conductiveplate.
 19. The wirebonding method of claim 18, wherein the stitch bondjoins the second end of the conductive bond wire to half or less of theconductive stud bump.
 20. The wirebonding method of claim 17, whereinthe stitch bond joins the second end of the conductive bond wire to halfor less of the conductive stud bump.